How can you set a specific user for a Docker container?

The correct choice for setting a specific user for a Docker container is achieved by using the -u option with the docker run command. This command allows you to specify the user that the container should run as, offering flexibility depending on the needs of your application and its permissions.

When you utilize the -u option, you can provide either the username or the user ID (UID). This is particularly useful in scenarios where certain processes within the container should not run as the root user for security reasons. By specifying a different user, you can limit the permissions of the running processes, thereby reducing the potential attack surface if an application were to be compromised.

Although specifying users can also be done within a Dockerfile using the USER instruction, the question specifically asks about the way to set a user at runtime, making the -u option in the docker run command the appropriate choice. Thus, this option effectively provides a direct means of controlling user permissions at the moment of container creation.